In CQRS the class is EventSourced which is part of the Event Sourcing pattern used in that project. This is in contrast to the EventSource class that is intended to be used for diagnostic tracing (System.Diagnostics.Tracing.EventSource).

So, to me they are conceptually different. However, I can see how you could think of using EventSource as a sort of messaging infrastructure. In general, I would recommend against that. I can think of a variety of reasons not do to this (e.g. EventSource only
supports a predefined set of types, non-standard use could cause future maintenance issues, etc.).